Docker Hub mailhog/mailhog does not support ARM

SImilar to #397, the images hosted on Docker Hub only support amd64 architecture and not the arm64 architecture. Unfortunately, downstream services might still be using these, like Space on-prem.

I understand the workaround for using the Dockerfile configuration (installs MailHog on top of golang image). But it would be nice to have an updated DockerHub image and also one that supports ARM. Thank you!